Filter medium and breather filter structure

ABSTRACT

Thermoplastic bicomponent binder fiber can be combined with other media, fibers and other filtration components to form a thermally bonded filtration media. The filtration media can be used in filter units, such as breather caps. Such filter units can be placed in the stream of a mobile fluid and can remove a particulate and/or fluid mist load from the mobile stream. The unique combination of media fiber, bicomponent binder fiber and other filtration additives and components provide a filtration media having unique properties in filtration applications.

RELATED APPLICATION

This application is a continuing application of U.S. application Ser.No. 13/591,669, filed Aug. 22, 2012, which is a continuing applicationof U.S. application Ser. No. 13/222,063, filed Aug. 31, 2011, which is acontinuing application of U.S. application Ser. No. 13/110,148, filedMay 18, 2011, which is a continuing application of U.S. application Ser.No. 11/381,010, filed May 1, 2006, now U.S. Pat. No. 8,057,567, whichissued on Nov. 15, 2011, which is a continuation-in-part of U.S.application Ser. No. 11/267,958 filed Nov. 4, 2005, now U.S. Pat. No.7,314,497, which issued on Jan. 1, 2008, which claims priority under 35U.S.C. §119(e) to U.S. provisional application Ser. Nos. 60/625,439filed Nov. 5, 2004 and 60/650,051 filed Feb. 4, 2005, the disclosures ofwhich are incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a formed layer, a filtration medium or media,and a filter having strength, compressibility and high capacity forparticulate removal from a moving fluid (air, gas, or liquid) stream.The filter and filter medium comprises a non-woven web made suitable forparticulate removal from mobile liquids and gasses using permeability,efficiency, loading and other filtration parameters. The inventionrelates to non-woven media layers obtaining sufficient tensile strength,wet strength, burst strength and other properties to survive the commonoperating conditions, such as variation in flow rate, temperature,pressure and particulate loading while removing substantial particulateloads from the fluid stream. The invention further relates to filterstructures comprising one or more layers of the particulate removingmedia with other layers of similar or dissimilar media. These layers canbe supported on a porous or perforate support and can provide mechanicalstability during filtering operations. These structures can be formedinto any of many filter forms such as panels, cartridge, inserts, etc.This disclosure relates to media layers and to methods of filtration ofgas and aqueous or non-aqueous liquids. Gaseous streams can include bothair and industrial waste gasses. Liquids can include water, fuels, oil,hydraulics, and others. The disclosure also relates to systems andmethods for separating entrained particulate from the gas or liquid. Theinvention also relates to hydrophobic fluids (such as oils or an aqueousoil emulsion or other oil mixture) that are entrained as aerosols, fromgas streams (for example airborne aerosol or aerosols in crankcasegases). Preferred arrangements also provide for filtration of other finecontaminants, for example carbon material, from the gas streams. Methodsfor conducting the separations are also provided.

BACKGROUND OF THE INVENTION

Non-woven webs for many end uses, including filtration media, have beenmanufactured for many years. Such structures can be made frombicomponent or core shell materials are disclosed in, for example,Wincklhofer et al., U.S. Pat. No. 3,616,160; Sanders, U.S. Pat. No.3,639,195; Perrotta, U.S. Pat. No. 4,210,540; Gessner, U.S. Pat. No.5,108,827; Nielsen et al., U.S. Pat. No. 5,167,764; Nielsen et al., U.S.Pat. No. 5,167,765; Powers et al., U.S. Pat. No. 5,580,459; Berger, U.S.Pat. No. 5,620,641; Hollingsworth et al., U.S. Pat. No. 6,146,436;Berger, U.S. Pat. No. 6,174,603; Dong, U.S. Pat. No. 6,251,224; Amsler,U.S. Pat. No. 6,267,252; Sorvari et al., U.S. Pat. No. 6,355,079;Hunter, U.S. Pat. No. 6,419,721; Cox et al., U.S. Pat. No. 6,419,839;Stokes et al., U.S. Pat. No. 6,528,439; Amsler, U.S. Pat. No. H2,086,U.S. Pat. No. 5,853,439; U.S. Pat. No. 6,171,355; U.S. Pat. No.6,355,076; U.S. Pat. No. 6,143,049; U.S. Pat. No. 6,187,073; U.S. Pat.No. 6,290,739; and U.S. Pat. No. 6,540,801; U.S. Pat. No. 6,530,969.This application incorporates by reference PCT Publication WO 01/47618published on Jul. 5, 2001, and PCT Publication WO 00/32295 published onJun. 8, 2000. Such structures have been applied and made by both airlaid and wet laid processing and have been used in fluid, both gaseousand air and aqueous and non-aqueous liquid filtration applications, withsome degree of success. In this regard we have found that the non-wovenwebs that are used for particulate removal from mobile fluids oftensuffer from a number of disadvantages.

Many attempts to obtain such non-woven structures with suitableperforate supports have been made. In many melt blown materials andlayers made with thermal lamination techniques, the resulting structuresoften obtain incorrect pore sizes, reduced efficiency, reducedpermeability, lack of strength or other problems rendering the media orfilter structure insufficient for useful fluid filtration applications.

A substantial need exists for filtration media, filter structures andfiltration methods that can be used for removing particulate materialsfrom fluid streams, and in particular gaseous streams such as air,aqueous, and non-aqueous liquids such as lubricating oils and hydraulicfluids. The invention provides such media, filtration structures andmethods and provides a unique media or media layer combinations thatachieve substantial permeability, high media strength, substantialefficiency and long filtration life.

Certain gas streams, such as blow-by gases from the crankcase of dieselengines, carry substantial amounts of entrained oils therein, asaerosol. The majority of the oil droplets within the aerosol aregenerally within the size of 0.1-5.0 microns. In addition, such gasstreams also carry substantial amounts of fine contaminant, such ascarbon contaminants. Such contaminants generally have an averageparticle size of about 0.5-3.0 microns. It is preferred to reduce theamount of such contaminants in these systems. A variety of efforts havebeen directed to the above types of concerns. The variables toward whichimprovements are desired generally concern the following:

(a) size/efficiency concerns; that is, a desire for good efficiency ofseparation while at the same time avoidance of a requirement for a largeseparator system;(b) cost/efficiency; that is, a desire for good or high efficiencywithout the requirement of substantially expensive systems; (c)versatility; that is, development of systems that can be adapted for awide variety of applications and uses, without significantre-engineering; and, (d) cleanability/regeneratability; that is,development of systems which can be readily cleaned (or regenerated) ifsuch becomes desired, after prolonged use.

BRIEF DESCRIPTION OF THE INVENTION

We have found a filter medium or media and a unique filter structurecapable of efficiently removing particulate from a mobile fluid streamunder a variety of conditions. The medium of the invention combines highstrength with excellent filtration properties. The invention comprises athermally bonded sheet, filter medium or filter containing a shaped orformed medium. Combining substantial proportions of an organic orinorganic media fiber, a bicomponent thermoplastic binder fiber,optionally a resin binder, a secondary fiber or other filtrationmaterials in a formed layer makes these sheet materials. The use of thebicomponent fiber enables the formation of a media layer or filterelement that can be formed with no separate resin binder or with minimalamounts of a resin binder that substantially reduces or prevents filmformation from the binder resin and also prevents lack of uniformity inthe media or element due to migration of the resin to a particularlocation of the media layer. The use of the bicomponent fiber permitsreduced compression, improves solidity, increases tensile strength andimproves utilization of media fiber such as glass fiber and other finefiber materials added to the media layer or filter element. Media fiberis that fiber that provides filtration properties to the media such ascontrollable pore size, permeability and efficiency. Further, thebicomponent fiber obtains improved processability during furnishformulation, sheet or layer formation and downstream processingincluding thickness adjustment, drying, cutting and filter elementformation. These components combine in various proportions to form ahigh strength material having substantial filtration capacity,permeability and filtration lifetime. The media of the invention canmaintain, intact, filtration capacity for substantial periods of time atsubstantial flow rates and substantial efficiency.

We have found a filter media and a unique filter structure capable ofremoving particulate from a fluid stream. The media comprises athermally bonded sheet, media, or filter made by combining a substantialproportion of a media fiber and a bicomponent thermoplastic binderfiber. The media can comprise glass fiber, a fiber blend of differingfiber diameters, a binder resin and a bicomponent thermoplastic binderfiber. Such a media can be made with optional secondary fibers and otheradditive materials. These components combine to form a high strengthmaterial having substantial flow capacity, permeability and highstrength. The media of the invention can maintain intact filtrationcapacity at high pressure for a substantial period of time. The mediaand filter operate at substantial flow rate, high capacity andsubstantial efficiency.

A first aspect of the invention comprises a filtration media or mediumhaving a thermally bonded non-woven structure.

A second aspect of the invention comprises a bilayer, tri layer ormultilayer (4-20, 4-64 or 4-100 layers) filtration medium or media. Inone embodiment, the medium comprises the mobile fluid passing firstthrough one layer comprising a loading layer and subsequently throughanother layer comprising an efficiency layer. A layer is a region of thematerial containing a different fibrous structure that may be attainedby changing the amount of fiber, the sizes or amount of different fibersused, or by changing the process conditions. Layers may be madeseparately and combined later or simultaneously.

A third aspect of the invention comprises a filter structure. Thestructure can comprise a media layer or can comprise a 2 to 100filtration media layer of the invention. Such layers can comprise aloading layer filtration media of the invention, and an efficiency layerfiltration media of the invention or combinations thereof also combinedwith other filtration layers, support structures and other filtercomponents.

A fourth aspect having high filtration performance comprises a depthloading media that does not compress or tear when subjected toapplication conditions or conversion processes. Such media can have lowsolidity as a result of relatively large spacing bicomponent and filterfiber.

A fifth aspect of the invention comprises a method of filtering themobile fluid phase having a particulate load using the filtrationaspects of the invention. The pervious support structure can support themedia under the influence of fluid under pressure passing through themedia and support. The mechanical support can comprise additional layersof the perforate support, wire support, a high permeability scrim orother support. This media commonly is housed in a filter element, panel,cartridge or other unit commonly used in the filtration of non-aqueousor aqueous liquids.

An additional aspect of the invention comprises a method of filteringwith preferred crankcase ventilation (CCV) filters. It particularlyconcerns use of advantageous filter media, in arrangements to filtercrankcase gases. The preferred media is provided in sheet form from awet laid process. It can be incorporated into filter arrangements, in avariety of ways, for example by a wrapping or coiling approach or byproviding in a panel construction. According to the present disclosure,filter constructions for preferred uses to filter blow-by gases fromengine crankcases are provided. Example constructions are provided. Alsoprovided are preferred filter element or cartridge arrangementsincluding the preferred type of media. Further, methods are provided.

Medium materials of the invention can be used in a variety of filterapplications including pulse clean and non-pulse cleaned filters fordust collection, gas turbines and engine air intake or inductionsystems; gas turbine intake or induction systems, heavy duty engineintake or induction systems, light vehicle engine intake or inductionsystems; vehicle cabin air; off road vehicle cabin air, disk drive air,photocopier-toner removal; HVAC filters in both commercial orresidential filtration applications. Paper filter elements are widelyused forms of surface loading media. In general, paper elements comprisedense mats of cellulose, synthetic or other fibers oriented across a gasstream carrying particulate material. The paper is generally constructedto be permeable to the gas flow, and to also have a sufficiently finepore size and appropriate porosity to inhibit the passage of particlesgreater than a selected size there-through. As the gases (fluids) passthrough the filter paper, the upstream side of the filter paper operatesthrough diffusion and interception to capture and retain selected sizedparticles from the gas (fluid) stream. The particles are collected as adust cake on the upstream side of the filter paper. In time, the dustcake also begins to operate as a filter, increasing efficiency.

In general, the invention can be used to filter air and gas streams thatoften carry particulate material entrained therein. In many instances,removal of some or all of the particulate material from the stream isnecessary for continued operations, comfort or aesthetics. For example,air intake streams to the cabins of motorized vehicles, to engines formotorized vehicles, or to power generation equipment; gas streamsdirected to gas turbines; and, air streams to various combustionfurnaces, often include particulate material therein. In the case ofcabin air filters it is desirable to remove the particulate matter forcomfort of the passengers and/or for aesthetics. With respect to air andgas intake streams to engines, gas turbines and combustion furnaces, itis desirable to remove the particulate material because it can causesubstantial damage to the internal workings to the various mechanismsinvolved. In other instances, production gases or off gases fromindustrial processes or engines may contain particulate materialtherein. Before such gases can be, or should be, discharged throughvarious downstream equipment or to the atmosphere, it may be desirableto obtain a substantial removal of particulate material from thosestreams. In general, the technology can be applied to filtering liquidsystems. In liquid filtering techniques, the collection mechanism isbelieved to be sieving when particles are removed through sizeexclusion. In a single layer the efficiency is that of the layer. Thecomposite efficiency in a liquid application is limited by theefficiency of the single layer with the highest efficiency. The liquidswould be directed through the media according to the invention, withparticulates therein trapped in a sieving mechanism. In liquid filtersystems, i.e. wherein the particulate material to be filtered is carriedin a liquid, such applications include aqueous and non-aqueous and mixedaqueous/non-aqueous applications such as water streams, lube oil,hydraulic fluid, fuel filter systems or mist collectors. Aqueous streamsinclude natural and man-made streams such as effluents, cooling water,process water, etc. Non-aqueous streams include gasoline, diesel fuel,petroleum and synthetic lubricants, hydraulic fluid and other esterbased working fluids, cutting oils, food grade oil, etc. Mixed streamsinclude dispersions comprising water in oil and oil in watercompositions and aerosols comprising water and a non-aqueous component.

The media of the invention comprises an effective amount of abicomponent binder fiber. “Bicomponent fiber” means a thermoplasticmaterial having at least one fiber portion with a melting point and asecond thermoplastic portion with a lower melting point. The physicalconfiguration of these fibers is typically in a “side-by-side” or“sheath-core” structure. In side-by-side structure, the two resins aretypically extruded in a connected form in a side-by-side structure. Onecould also use lobed fibers where the tips have lower melting pointpolymer. “Glass fiber” is fiber made using glass of various types. Theterm “secondary fibers” can include a variety of different fibers fromnatural synthetic or specialty sources. Such fibers are used to obtain athermally bonded media sheet, media, or filter, and can also aid inobtaining appropriate pore size, permeability, efficiency, tensilestrength, compressibility, and other desirable filter properties. Themedium of the invention is engineered to obtain the appropriatesolidity, thickness, basis weight, fiber diameter, pore size,efficiency, permeability, tensile strength, and compressibility toobtain efficient filtration properties when used to filter a certainmobile stream. Solidity is the solid fiber volume divided by the totalvolume of the filter medium, usually expressed as a percentage. Forexample, the media used in filtering a dust-laden air stream can bedifferent from a media used for filtering a water or oil aerosol from anair stream. Further, the media used to remove particulates from a liquidstream can be different than a media used to remove particulates from angaseous stream. Each application of the technology of the inventionobtains from a certain set of operating parameters as discussed below.

The media of the invention can be made from a media fiber. Media fibersinclude a broad variety of fibers having the correct diameter, lengthand aspect ratio for use in filtration applications. One preferred mediafiber is a glass fiber. A substantial proportion of glass fiber can beused in the manufacture of the media of the invention. The glass fiberprovides pore size control and cooperates with the other fibers in themedia to obtain a media of substantial flow rate, high capacity,substantial efficiency and high wet strength. The term glass fiber“source” means a glass fiber composition characterized by an averagediameter and aspect ratio that is made available as a distinct rawmaterial. Blends of one or more of such sources do not read on singlesources.

We have found that by blending various proportions of bicomponent andmedia fiber that substantially improved strength and filtration can beobtained. Further, blending various fiber diameters can result inenhanced properties. Wet laid or dry laid processes can be used. Inmaking the media of the invention, a fiber mat is formed using eitherwet or dry processing. The mat is heated to melt thermoplastic materialsto form the media by internally adhering the fibers. The bicomponentfiber used in the media of the invention permits the fiber to fuse intoa mechanically stable sheet, media, or filter. The bicomponent fiberhaving a thermally bonding exterior sheath causes the bicomponent fiberto bind with other fibers in the media layer. The bicomponent fiber canbe used with an aqueous or solvent based resin and other fibers to formthe medium.

In the preferred wet laid processing, the medium is made from an aqueousfurnish comprising a dispersion of fibrous material in an aqueousmedium. The aqueous liquid of the dispersion is generally water, but mayinclude various other materials such as pH adjusting materials,surfactants, defoamers, flame retardants, viscosity modifiers, mediatreatments, colorants and the like. The aqueous liquid is usuallydrained from the dispersion by conducting the dispersion onto a screenor other perforated support retaining the dispersed solids and passingthe liquid to yield a wet paper composition. The wet composition, onceformed on the support, is usually further dewatered by vacuum or otherpressure forces and further dried by evaporating the remaining liquid.After liquid is removed, thermal bonding takes place typically bymelting some portion of the thermoplastic fiber, resin or other portionof the formed material. The melt material binds the component into alayer.

The media of this invention can be made on equipment of any scale fromlaboratory screens to commercial-sized papermaking. For a commercialscale process, the bicomponent mats of the invention are generallyprocessed through the use of papermaking-type machines such ascommercially available Fourdrinier, wire cylinder, Stevens Former, RotoFormer, Inver Former, Venti Former, and inclined Delta Former machines.Preferably, an inclined Delta Former machine is utilized. The generalprocess involves making a dispersion of bicomponent fibers, glassfibers, or other medium material in an aqueous liquid, draining theliquid from the resulting dispersion to yield a wet composition, andadding heat to form, bond and dry the wet non-woven composition to formthe useful medium.

DETAILED DESCRIPTION OF THE INVENTION

The media of the invention relates to a composite, non-woven, air laidor wet laid media having formability, stiffness, tensile strength, lowcompressibility, and mechanical stability for filtration properties;high particulate loading capability, low pressure drop during use and apore size and efficiency suitable for use in filtering fluids.Preferably, the filtration media of the invention is typically wet laidand is made up of randomly oriented array of media fiber, such as aglass fiber, and a bicomponent fiber. These fibers are bonded togetherusing the bicomponent fiber and sometimes with the addition of a binderresin to the invention. The media that can be used in the filters andmethods of the invention contain an inorganic fiber, a bicomponentbinder fiber, a binder and other components. The media fiber of theinvention can include organic fibers such as natural and syntheticfibers including polyolefin, polyester, nylon, cotton, wool, etc.fibers. The media fiber of the invention can include inorganic fibersuch as glass, metal, silica, polymeric fibers, and other relatedfibers.

The preferred filter structure of the invention comprises at least onemedia layer of the invention supported on a mechanically stableperforate support structure. The media and support are often packaged ina panel, cartridge or other filter format. The media layer can have adefined pore size for the purpose of removing particulates from fluidstreams having a particle size of about 0.01 to 100 micrometers, fromgas streams containing liquids in the form of a mist having droplet sizeof about 0.01 to 100 micrometers, from aqueous streams having a particlesize of about 0.1 to 100 micrometers from non-aqueous streams having aparticle size of about 0.05 to 100 micrometers or from fuel, lubricantor hydraulic streams having a particle size of about 0.05 to 100micrometers. Additional information regarding filter structures can befound below.

Mechanical attributes are important for filter media including wet anddry tensile strength, burst strength, etc. Compressibilitycharacteristic is important. Compressibility is the resistance (i.e.) tocompression or deformation in the direction of fluid flow through themedia. This must be sufficient to maintain a material's thickness andthereby maintain its pore structure and filtration flow and particulateremoval performance. Many high efficiency wet laid materials usingconventional resin saturation, melt blown materials, and other air laidmaterials lack this compressive strength and collapse under pressure.This is especially a problem with liquid filters, but can also be aproblem with gas filters. In addition, media that are pleated must havesufficient tensile strength for processing into a finished filter withan integrated pleated structure. For example, pleating, corrugating,winding, threading, unwinding, laminating, coating, ultrasonicallywelding, dimpling or various other rolled goods operations. Materialswithout sufficient tensile strength may break during these processes.

Compressive strength is defined here as the percent change in thicknesswhen the pressure applied during thickness measurement is increased.Compressive strengths typical of the materials made by the invention areas follows:

Compressive strength when pressure varied from 1.25 lb-in⁻² to 40lb-in⁻²: 8% to 40%Compressive strength when pressure varied from 0.125 lb-in⁻² to 0.625lb-in⁻²: 10% to 20%

Tensile strength is defined here as the peak load is typically expressedas a peak load per unit width of dry media when running a forcedeflection test. The tensile strength will usually vary with sheetorientation. The orientation of interest for rolled goods operations isthe machine direction. The range of machine direction tensile strengthfor these bicomponent sheets is from about 2 lb/(in width) to about 40lb/(in width) or 5 lb/(in width) to about 35 lb/(in width). This willobviously vary with thickness and quantity of bicomponent fibers.

A filter with a gradient structure where the media pores become smalleron the downstream side is often helpful. In other words, the porousstructure becomes continuously denser going from upstream to downstreamside. As a result, the particles or contaminants to be filtered are ableto penetrate to varying depths dependent on particle size. This causesthe particles or contaminants to be distributed throughout the depth ofthe filter material, reducing the build up of pressure drop, andextending the life of the filter.

In other cases, for example, when filtering oil or water mists out ofgas streams, it is often advantageous to use a filter with a gradientstructure where the media pores become larger on the downstream side. Inother words, the porous structure becomes less dense going from theupstream to downstream side. Generally, this results in less fibersurface area in the downstream regions. As a result, the captureddroplets are forced to come together and coalesce into larger droplets.At the same time, these downstream regions are more open and allow thenow larger droplets to drain from the filter material. These types ofgradient structures may be made in a single layer by stratifying thefiner fibers either downstream or upstream, or by forming and combiningseveral discrete layers by applying a series of differing furnishes.Often, when combining discrete layers, the laminating techniques resultin loss of useful filtration surface area. This is true of most adhesivelaminating systems performed by coating one surface with adhesive andthen contacting the layers together, whether this is done in ahomogeneous coating or in a dot pattern. The same is true ofpoint-bonded material using ultrasonic bonding. A unique feature whenusing bicomponent fibers in the filter sheet or material is thebicomponent not only bonds the fibers of individual layers together, butcan also act to bond the layers together. This has been accomplished inconventional heat lamination as well as through pleating.

The filter media of the present invention is typically suited for highefficiency filtration properties such that fluids, including air andother gasses, aqueous and non-aqueous fuel, lubricant, hydraulic orother such fluids can be rapidly filtered to remove contaminatingparticulates.

Pressure-charged diesel engines often generate “blow-by” gases, i.e., aflow of air-fuel mixture leaking past pistons from the combustionchambers. Such “blow-by gases” generally comprise a gas phase, forexample air or combustion off gases, carrying therein: (a) hydrophobicfluid (e.g., oil including fuel aerosol) principally comprising 0.1-5.0micron droplets (principally, by number); and, (b) carbon contaminantfrom combustion, typically comprising carbon particles, a majority ofwhich are about 0.1-10 microns in size. Such “blow-by gases” aregenerally directed outwardly from the engine block, through a blow-byvent. Herein when the term “hydrophobic” fluids is used in reference tothe entrained liquid aerosol in gas flow, reference is meant tonon-aqueous fluids, especially oils. Generally such materials areimmiscible in water. Herein the term “gas” or variants thereof, used inconnection with the carrier fluid, refers to air, combustion off gases,and other carrier gases for the aerosol. The gases may carry substantialamounts of other components. Such components may include, for example,copper, lead, silicone, aluminum, iron, chromium, sodium, molybdenum,tin, and other heavy metals. Engines operating in such systems astrucks, farm machinery, boats, buses, and other systems generallycomprising diesel engines, may have significant gas flows contaminatedas described above. For example, flow rates can be about 2-50 cubic feetper minute (cfm), typically 5 to 10 cfm. In such an aerosol separator infor example a turbocharged diesel engine, air is taken to the enginethrough an air filter, cleaning the air taken in from the atmosphere. Aturbo pushes clean air into engine. The air undergoes compression andcombustion by engaging with pistons and fuel. During the combustionprocess, the engine gives off blow-by gases. A filter arrangement is ingas flow communication with engine and cleans the blow-by gases that arereturned to the air intake or induction system. The gasses and air isagain pulled through by the turbo and into the engine. The filterarrangement in gas flow communication is used for separating ahydrophobic liquid phase from a gaseous stream (sometimes referred toherein as a coalescer/separator arrangement) is provided. In operation,a contaminated gas flow is directed into the coalescer/separatorarrangement. Within the arrangement, the fine oil phase or aerosol phase(i.e., hydrophobic phase) coalesces. The arrangement is constructed sothat as the hydrophobic phase coalesces into droplets, it will drain asa liquid such that it can readily be collected and removed from thesystem. With preferred arrangements as described herein below, thecoalescer or coalescer/separator, especially with the oil phase in partloaded thereon, operates as a filter for other contaminant (such ascarbon contaminant) carried in the gas stream. Indeed, in some systems,as the oil is drained from the system, it will provide someself-cleaning of the coalescer because the oil will carry therein aportion of the trapped carbon contaminant. The principles according tothe present disclosure can be implemented in single stage arrangementsor multistage arrangements. In many of the figures, multistagearrangements are depicted. In the general descriptions, we will explainhow the arrangements could be varied to a single stage arrangement, ifdesired.

We have found, in one embodiment, that two filter media of thisdescription can be combined in one embodiment. A loading layer and anefficiency layer can be used, each of said layers having distinctstructures and filtration properties, to form a composite layer. Theloading layer is followed in a fluid pathway by an efficiency layer. Theefficiency layer is a highly efficient layer having suitable porosity,efficiency, permeability and other filtration characteristics to removeany remaining harmful particulate from the fluid stream as the fluidpasses through the filter structure. The loading filtration media of theinvention has a basis weight of about 30 to about 100 g-m⁻². Theefficiency layer has a basis weight of about 40 to about 150 g-m⁻². Theloading layer has an average pore size of about 5 to about 30micrometers. The efficiency layer has a pore size smaller than theloading layer that ranges from about 0.5 to about 3 micrometers. Theloading layer has a permeability that ranges from about 50 to 200ft-min⁻¹. The efficiency layer has a permeability of about 5 to 30ft-min⁻¹. The loading layer or the efficiency layer of the invention hasa wet bursting strength of greater than about 5 lb-in⁻², typically about10 to about 25 lb-in⁻². The combined filtration layer has a permeabilityof about 4 to 20 ft-min⁻¹; a wet burst strength of 10 to 20 lb-in⁻² anda basis weight of 100 to 200 g-m⁻².

Various combinations of polymers for the bicomponent fiber may be usefulin the present invention, but it is important that the first polymercomponent melt at a temperature lower than the melting temperature ofthe second polymer component and typically below 205° C. Further, thebicomponent fibers are integrally mixed and evenly dispersed with thepulp fibers. Melting of the first polymer component of the bicomponentfiber is necessary to allow the bicomponent fibers to form a tackyskeletal structure, which upon cooling, captures and binds many of thesecondary fibers, as well as binds to other bicomponent fibers.

In the sheath-core structure, the low melting point (e.g., about 80 to205° C.) thermoplastic is typically extruded around a fiber of thehigher melting (e.g., about 120 to 260° C.) point material. In use, thebicomponent fibers typically have a fiber diameter of about 5 to 50micrometers often about 10 to 20 micrometers and typically in a fiberform generally have a length of 0.1 to 20 millimeters or often have alength of about 0.2 to about 15 millimeters. Such fibers can be madefrom a variety of thermoplastic materials including polyolefins (such aspolyethylenes, polypropylenes), polyesters (such as polyethyleneterephthalate, polybutylene terephthalate, PCT), nylons including nylon6, nylon 6,6, nylon 6,12, etc. Any thermoplastic that can have anappropriate melting point can be used in the low melting component ofthe bicomponent fiber while higher melting polymers can be used in thehigher melting “core” portion of the fiber. The cross-sectionalstructure of such fibers can be, as discussed above, the “side-by-side”or “sheath-core” structure or other structures that provide the samethermal bonding function. One could also use lobed fibers where the tipshave lower melting point polymer. The value of the bicomponent fiber isthat the relatively low molecular weight resin can melt under sheet,media, or filter forming conditions to act to bind the bicomponentfiber, and other fibers present in the sheet, media, or filter makingmaterial into a mechanically stable sheet, media, or filter.

Typically, the polymers of the bicomponent (core/shell or sheath andside-by-side) fibers are made up of different thermoplastic materials,such as for example, polyolefin/polyester (sheath/core) bicomponentfibers whereby the polyolefin, e.g. polyethylene sheath, melts at atemperature lower than the core, e.g. polyester. Typical thermoplasticpolymers include polyolefins, e.g. polyethylene, polypropylene,polybutylene, and copolymers thereof, polytetrafluoroethylene,polyesters, e.g. polyethylene terephthalate, polyvinyl acetate,polyvinyl chloride acetate, polyvinyl butyral, acrylic resins, e.g.polyacrylate, and polymethylacrylate, polymethylmethacrylate,polyamides, namely nylon, polyvinyl chloride, polyvinylidene chloride,polystyrene, polyvinyl alcohol, polyurethanes, cellulosic resins, namelycellulosic nitrate, cellulosic acetate, cellulosic acetate butyrate,ethyl cellulose, etc., copolymers of any of the above materials, e.g.ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers,styrene-butadiene block copolymers, Kraton rubbers and the like.Particularly preferred in the present invention is a bicomponent fiberknown as 271P available from DuPont. Others fibers include FIT 201,Kuraray N720 and the Nichimen 4080 and similar materials. All of thesedemonstrate the characteristics of cross-linking the sheath poly uponcompletion of first melt. This is important for liquid applicationswhere the application temperature is typically above the sheath melttemperature. If the sheath does not fully crystallize then the sheathpolymer will remelt in application and coat or damage downstreamequipment and components.

Media fibers are fibers that can aid in filtration or in forming astructural media layer. Such fiber is made from a number of bothhydrophilic, hydrophobic, oleophilic, and oleophobic fibers. Thesefibers cooperate with the glass fiber and the bicomponent fiber to forma mechanically stable, but strong, permeable filtration media that canwithstand the mechanical stress of the passage of fluid materials andcan maintain the loading of particulate during use. Such fibers aretypically monocomponent fibers with a diameter that can range from about0.1 to about 50 micrometers and can be made from a variety of materialsincluding naturally occurring cotton, linen, wool, various cellulosicand proteinaceous natural fibers, synthetic fibers including rayon,acrylic, aramide, nylon, polyolefin, polyester fibers. One type ofsecondary fiber is a binder fiber that cooperates with other componentsto bind the materials into a sheet. Another type a structural fibercooperates with other components to increase the tensile and burststrength the materials in dry and wet conditions. Additionally, thebinder fiber can include fibers made from such polymers as polyvinylchloride, polyvinyl alcohol. Secondary fibers can also include inorganicfibers such as carbon/graphite fiber, metal fiber, ceramic fiber andcombinations thereof.

Thermoplastic fibers include, but are not limited to, polyester fibers,polyamide fibers, polypropylene fibers, copolyetherester fibers,polyethylene terephthalate fibers, polybutylene terephthalate fibers,polyetherketoneketone (PEKK) fibers, polyetheretherketone (PEEK) fibers,liquid crystalline polymer (LCP) fibers, and mixtures thereof. Polyamidefibers include, but are not limited to, nylon 6, 66, 11, 12, 612, andhigh temperature “nylons” (such as nylon 46) including cellulosicfibers, polyvinyl acetate, polyvinyl alcohol fibers (including varioushydrolysis of polyvinyl alcohol such as 88% hydrolyzed, 95% hydrolyzed,98% hydrolyzed and 99.5% hydrolyzed polymers), cotton, viscose rayon,thermoplastic such as polyester, polypropylene, polyethylene, etc.,polyvinyl acetate, polylactic acid, and other common fiber types. Thethermoplastic fibers are generally fine (about 0.5-20 denier diameter),short (about 0.1-5 cm long), staple fibers, possibly containingprecompounded conventional additives, such as antioxidant, stabilizers,lubricants, tougheners, etc. In addition, the thermoplastic fibers maybe surface treated with a dispersing aid. The preferred thermoplasticfibers are polyamide and polyethylene terephthalate fibers, with themost preferred being polyethylene terephthalate fibers.

The preferred media fiber comprises a glass fiber used in media of thepresent invention include glass types known by the designations: A, C,D, E, Zero Boron E, ECR, AR, R, S, S-2, N, and the like, and generally,any glass that can be made into fibers either by drawing processes usedfor making reinforcement fibers or spinning processes used for makingthermal insulation fibers. Such fiber is typically used as a diameterabout 0.1 to 10 micrometers and an aspect ratio (length divided bydiameter) of about 10 to 10000. These commercially available fibers arecharacteristically sized with a sizing coating. Such coatings cause theotherwise ionically neutral glass fibers to form and remain in bundles.Glass fiber in diameter less than about 1 micron is not sized. Largediameter chopped glass is sized.

Manufacturers of glass fibers commonly employ sizes such as this. Thesizing composition and cationic antistatic agent eliminates fiberagglomeration and permits a uniform dispersion of the glass fibers uponagitation of the dispersion in the tank. The typical amount of glassfibers for effective dispersion in the glass slurry is within the rangeof 50% to about 90%, and most preferably about 50-80%, by weight of thesolids in the dispersion. Blends of glass fibers can substantially aidin improving permeability of the materials. We have found that combininga glass fiber having an average fiber diameter of about 0.3 to 0.5micrometer, a glass fiber having an average fiber diameter of about 1 to2 micrometers, a glass fiber having an average fiber diameter of about 3to 6 micrometers, a glass fiber with a fiber diameter of about 6 to 10micrometers, and a glass fiber with a fiber diameter of about 10 to 100micrometers in varying proportions can substantially improvepermeability. We believe the glass fiber blends obtain a controlled poresize resulting in a defined permeability in the media layer. Binderresins can typically comprise water-soluble or water sensitive polymermaterials. Its polymer materials are typically provided in either dryform or aqueous dispersions. Such useful polymer materials includeacrylic polymers, ethylene vinyl acetate polymers, ethylene vinylpolyvinyl alcohol, ethylene vinyl alcohol polymers, polyvinylpyrrolidone polymers, and natural gums and resins useful in aqueoussolution.

We have surprisingly found that the media of the invention have asurprising thermal property. The media after formation and thermalbonding at or above the melt temperature of the lower melting portion ofthe bicomponent fiber, can be used at temperatures above that meltingtemperature. Once thermally formed, the media appears to be stable attemperatures at which the media should lose mechanical stability due tothe softening or melting of the fiber. We believe that there is someinteraction in the bonded mass that prevents the melting of the fiberand the resulting failure of the media. Accordingly, the media can beused with a mobile gaseous or liquid phase at a temperature equal to or10 to 100° F. above the melt temperature of the lower melting portion ofthe bicomponent fiber. Such applications include hydraulic fluidfiltration, lubricant oil filtration, hydrocarbon fuel filtration, hotprocess gas filtration, etc.

Binder resins can be used to help bond the fiber into a mechanicallystable media layer. Such thermoplastic binder resin materials can beused as a dry powder or solvent system, but are typically aqueousdispersions (a latex or one of a number of lattices) of vinylthermoplastic resins. A resinous binder component is not necessary toobtain adequate strength for the papers of this invention, but can beused. Resin used as binder can be in the form of water soluble ordispersible polymer added directly to the paper making dispersion or inthe form of thermoplastic binder fibers of the resin materialintermingled with the aramid and glass fibers to be activated as abinder by heat applied after the paper is formed. Resins include vinylacetate materials, vinyl chloride resins, polyvinyl alcohol resins,polyvinyl acetate resins, polyvinyl acetyl resins, acrylic resins,methacrylic resins, polyamide resins, polyethylene vinyl acetatecopolymer resins, thermosetting resins such as urea phenol, ureaformaldehyde, melamine, epoxy, polyurethane, curable unsaturatedpolyester resins, polyaromatic resins, resorcinol resins and similarelastomer resins. The preferred materials for the water soluble ordispersible binder polymer are water soluble or water dispersiblethermosetting resins such as acrylic resins. methacrylic resins,polyamide resins, epoxy resins, phenolic resins, polyureas,polyurethanes, melamine formaldehyde resins, polyesters and alkydresins, generally, and specifically, water soluble acrylic resins.methacrylic resins, polyamide resins, that are in common use in thepapermaking industry. Such binder resins typically coat the fiber andadhere fiber to fiber in the final non-woven matrix. Sufficient resin isadded to the furnish to fully coat the fiber without causing film overof the pores formed in the sheet, media, or filter material. The resincan be added to the furnish during papermaking or can be applied to themedia after formation.

The latex binder used to bind together the three-dimensional non-wovenfiber web in each non-woven layer or used as the additional adhesive,can be selected from various latex adhesives known in the art. Theskilled artisan can select the particular latex adhesive depending uponthe type of cellulosic fibers that are to be bound. The latex adhesivemay be applied by known techniques such as spraying or foaming.Generally, latex adhesives having from 15 to 25% solids are used. Thedispersion can be made by dispersing the fibers and then adding thebinder material or dispersing the binder material and then adding thefibers. The dispersion can, also, be made by combining a dispersion offibers with a dispersion of the binder material. The concentration oftotal fibers in the dispersion can range from 0.01 to 5 or 0.005 to 2weight percent based on the total weight of the dispersion. Theconcentration of binder material in the dispersion can range from 10 to50 weight percent based on the total weight of the fibers.

Non-woven media of the invention can contain secondary fibers made froma number of both hydrophilic, hydrophobic, oleophilic, and oleophobicfibers. These fibers cooperate with the glass fiber and the bicomponentfiber to form a mechanically stable, but strong, permeable filtrationmedia that can withstand the mechanical stress of the passage of fluidmaterials and can maintain the loading of particulate during use.Secondary fibers are typically monocomponent fibers with a diameter thatcan range from about 0.1 to about 50 micrometers and can be made from avariety of materials including naturally occurring cotton, linen, wool,various cellulosic and proteinaceous natural fibers, synthetic fibersincluding rayon, acrylic, aramide, nylon, polyolefin, polyester fibers.One type of secondary fiber is a binder fiber that cooperates with othercomponents to bind the materials into a sheet. Another type of secondaryfiber is a structural fiber that cooperates with other components toincrease the tensile and burst strength the materials in dry and wetconditions. Additionally, the binder fiber can include fibers made fromsuch polymers as polyvinyl chloride, polyvinyl alcohol. Secondary fiberscan also include inorganic fibers such as carbon/graphite fiber, metalfiber, ceramic fiber and combinations thereof.

The secondary thermoplastic fibers include, but are not limited to,polyester fibers, polyamide fibers, polypropylene fibers,copolyetherester fibers, polyethylene terephthalate fibers, polybutyleneterephthalate fibers, polyetherketoneketone (PEKK) fibers,polyetheretherketone (PEEK) fibers, liquid crystalline polymer (LCP)fibers, and mixtures thereof. Polyamide fibers include, but are notlimited to, nylon 6, 66, 11, 12, 612, and high temperature “nylons”(such as nylon 46) including cellulosic fibers, polyvinyl acetate,polyvinyl alcohol fibers (including various hydrolysis of polyvinylalcohol such as 88% hydrolyzed, 95% hydrolyzed, 98% hydrolyzed and 99.5%hydrolyzed polymers), cotton, viscose rayon, thermoplastic such aspolyester, polypropylene, polyethylene, etc., polyvinyl acetate,polylactic acid, and other common fiber types. The thermoplastic fibersare generally fine (about 0.5-20 denier diameter), short (about 0.1-5 cmlong), staple fibers, possibly containing precompounded conventionaladditives, such as antioxidant, stabilizers, lubricants, tougheners,etc. In addition, the thermoplastic fibers may be surface treated with adispersing aid. The preferred thermoplastic fibers are polyamide andpolyethylene terephthalate fibers, with the most preferred beingpolyethylene terephthalate fibers.

Fluoro-organic wetting agents useful in this invention for addition tothe fiber layers are organic molecules represented by the formula

R_(f)-G

wherein R_(f) is a fluoroaliphatic radical and G is a group whichcontains at least one hydrophilic group such as cationic, anionic,nonionic, or amphoteric groups. Nonionic materials are preferred. R_(f)is a fluorinated, monovalent, aliphatic organic radical containing atleast two carbon atoms. Preferably, it is a saturated perfluoroaliphaticmonovalent organic radical. However, hydrogen or chlorine atoms can bepresent as substituents on the skeletal chain. While radicals containinga large number of carbon atoms may function adequately, compoundscontaining not more than about 20 carbon atoms are preferred since largeradicals usually represent a less efficient utilization of fluorine thanis possible with shorter skeletal chains. Preferably, R_(f) containsabout 2 to 8 carbon atoms.

The cationic groups that are usable in the fluoro-organic agentsemployed in this invention may include an amine or a quaternary ammoniumcationic group which can be oxygen-free (e.g., —NH₂) oroxygen-containing (e.g., amine oxides). Such amine and quaternaryammonium cationic hydrophilic groups can have formulas such as —NH₂,—(NH₃)X, —(NH(R²)₂)X, —(NH(R²)₃)X, or —N(R₂)₂→O, where x is an anioniccounterion such as halide, hydroxide, sulfate, bisulfate, orcarboxylate, R² is H or C₁₋₁₈ alkyl group, and each R² can be the sameas or different from other R² groups. Preferably, R² is H or a C₁₋₁₆alkyl group and X is halide, hydroxide, or bisulfate.

The anionic groups which are usable in the fluoro-organic wetting agentsemployed in this invention include groups which by ionization can becomeradicals of anions. The anionic groups may have formulas such as —COOM,—SO₃M, —OSO₃M, —PO₃HM, —OPO₃M₂, or —OPO₃HM, where M is H, a metal ion,(NR¹ ₄)⁺, or (SR¹ ₄)⁺, where each R¹ is independently H or substitutedor unsubstituted C₁-C₆ alkyl. Preferably M is Na⁺ or K. The preferredanionic groups of the fluoro-organo wetting agents used in thisinvention have the formula —COOM or —SO₃M. Included within the group ofanionic fluoro-organic wetting agents are anionic polymeric materialstypically manufactured from ethylenically unsaturated carboxylic mono-and diacid monomers having pendent fluorocarbon groups appended thereto.Such materials include surfactants obtained from 3M Corporation known asFC-430 and FC-431.

The amphoteric groups which are usable in the fluoro-organic wettingagent employed in this invention include groups which contain at leastone cationic group as defined above and at least one anionic group asdefined above.

The nonionic groups which are usable in the fluoro-organic wettingagents employed in this invention include groups which are hydrophilicbut which under pH conditions of normal agronomic use are not ionized.The nonionic groups may have formulas such as —O(CH₂CH₂)_(x)OH where xis greater than 1, —SO₂NH₂, —SO₂NHCH₂CH₂OH, —SO₂N(CH₂CH₂H)₂, —CONH₂,—CONHCH₂CH₂OH, or —CON(CH₂CH₂OH)₂. Examples of such materials includematerials of the following structure:

F(CF₂CF₂)_(n)—CH₂CH₂O—(CH₂CH₂O)_(m)—H

wherein n is 2 to 8 and m is 0 to 20.

Other fluoro-organic wetting agents include those cationicfluorochemicals described, for example in U.S. Pat. Nos. 2,764,602;2,764,603; 3,147,064 and 4,069,158. Such amphoteric fluoro-organicwetting agents include those amphoteric fluorochemicals described, forexample, in U.S. Pat. Nos. 2,764,602; 4,042,522; 4,069,158; 4,069,244;4,090,967; 4,161,590 and 4,161,602. Such anionic fluoro-organic wettingagents include those anionic fluorochemicals described, for example, inU.S. Pat. Nos. 2,803,656; 3,255,131; 3,450,755 and 4,090,967.

There are numerous methods of modifying the surface of the fibers.Fibers that enhance drainage can be used to manufacture the media.Treatments can be applied during the manufacture of the fibers, duringmanufacture of the media or after manufacture of the media as a posttreatment. Numerous treatment materials are available such asfluorochemicals or silicone containing chemicals that increase thecontact angle. One example would be DuPont Zonyl fluorochemicals such as8195. Numerous fibers incorporated into filter media can be treated toenhance their drainage capability. Bicomponent fibers composed ofpolyester, polypropylene or other synthetic polymers can be treated.Glass fibers, synthetic fibers, ceramic, or metallic fibers can also betreated. We are utilizing various fluorochemicals such as DuPont #8195,#7040 and #8300. The media grade is composed of 50% by mass DuPont 271Pbicomponent fiber cut 6 mm long, 40% by weight DuPont Polyester 205 WSDcut 6 mm, and 10% by mass Owens Corning DS-9501-11W Advantex cut to 6mm. This media grade was produced using the wet laid process on aninclined wire which optimizes the distribution of the fibers anduniformity of the media. The media is being post treated in media orelement form with a dilute mixture of Zonyl incorporating a fugitivewetting agent (isopropyl alcohol), and DI water. The treated, wrappedelement pack is dried and cured at 240 F to remove the liquid andactivate the fluorochemical.

Examples of such materials are DuPont Zonyl FSN and DuPont Zonyl FSOnonionic surfactants. Another aspect of additives that can be used inthe polymers of the invention include low molecular weight fluorocarbonacrylate materials such as 3M's Scotchgard material having the generalstructure:

CF₃(CX₂)_(n)-acrylate

wherein X is —F or —CF₃ and n is 1 to 7.

The following table sets forth the useful parameters of the layers ofthe invention:

TABLE 1 Bicomponent Bicomponent Fiber Glass Glass Fiber Fiber DiameterFiber Diameter Fluid Contaminant Layer % Micrometer % Micrometer AirIndustrial 1, 2 or 20-80  5-15 80-20 0.1-5   Mist more 50 13.0 50 1.6Air Industrial 1 50  5-15 80-20 1.6 Mist 14.0 12.5 1.5 37.5 AirIndustrial 1 20-80  5-15 80-20 1.5 Mist 14.0 50 Air Diesel Engine 120-80  5-15 0 11 Crankcase 50 14.0 10 Blowby Air Diesel Engine 1 10-30 5-15 35-50 0.4-3.4 Crankcase 12 Blowby Diesel Soot 1  1-40  5-15 60-990.1-5   Engine 2 20 12.0 80 0.32-0.51 Lube Oil 3 or more 20 12.0 80 0.4320 12.0 80 0.32 Diesel fuel Particulate 1 50 10-14 30-50 0.2-0.8 2 50-6510-14 25-50 0.4-1   3 50-70 10-14 13-33 1.0-1.5 4 50 10-14  0-50 2.6Hydraulic Particulate  1, 20-80  5-15 80-20 0.1-5    2, 50 12.0 500.8-2.6  3, 50 12.0 33 1 4 or more 50 12.0 33 0.8 50 12.0 50 0.51 AirParticulate 1 or 2 80-98 10-15  3-12 0.5-2   Air Particulate 1 90 12.010 0.6 Air Particulate 1 95 12.0 5 0.6 Air Particulate 1 97 12.0 3 0.6Secondary Thickness Secondary Fiber Basis mm Fiber Diameter Weight 0.1250.625 1.5 Fluid Contaminant % Micrometer g-m⁻² lb-in⁻² lb-in⁻² lb-in⁻²Air Industrial  0-10 20-80 0.2-0.8 0.2-0.8 0.2-0.8 Mist 0.1-10  62.30.510 0.430 0.410 Air Industrial 128.2 1.27 .993 .892 Mist AirIndustrial 122.8 1.14 .922 .833 Mist Air Diesel Engine     5-50% 0.5-15 20-80 0.2-0.8 0.2-0.8 0.2-0.8 Crankcase    10-40% 10-15 65.7 0.690 0.580.530 Blowby Poly Polyester Air Diesel Engine 20-55  7-13 134 0.69Crankcase 15-25 Latex resin Blowby Diesel Soot  0-20 10-50 0.2-0.8Engine 17 40 0.3 Lube Oil 17 32 0.25 0 28 0.2 Diesel fuel Particulate10-15 10 30-50 0.18-0.31 13-50 12-14 17 17 Hydraulic Particulate 10-2010-50 0.2-0.8 18 32 0.23 18 37 0.26 39 0.25 34 0.18 Air Particulate 40-350 0.2-2   Air Particulate 45 0.25 Air Particulate 110 0.51 AirParticulate 300 1.02 3160 DOP Mean Efficiency Compressibility SolidityMD Fold Pore 10.5 fpm % change from at 0.125 Perm Tensile Size % at 0.30.125 lb-inch⁻² lb-inch⁻² ft- lb/(in Micro- Micro- Fluid Contaminant to0.5 lb-inch⁻² % min⁻¹ width) meter meter Air Industrial 15  2-10  50-500 5-15  5-20  5-25 Mist 6.9 204 3.9 17.8 12.0 Air Industrial 22 5.6 686.9 15.6 26.3 Mist Air Industrial 19 6 50 8.6 14.4 39.7 Mist Air DieselEngine 14 6.7  50-300  5-15  5-20  5-20 Crankcase 392 2.6 43 6.0 BlowbyAir Diesel Engine 33 Crankcase Blowby Diesel fuel Particulate  6-5401.5-41  Diesel Soot  2-10 0.1-30  0.5-10  Engine 4 7 2 Lube Oil 5 6 1.26 4 1 Hydraulic Particulate  5-200 0.5-30  180 19 94 6.9 23 2.6 6.7 0.94Air Particulate 10-25  20-200 10-30 Air Particulate 13 180 26 AirParticulate 17 90 33 Air Particulate 22 30 12

We have found improved technology of enhanced internal bond betweenfiber and fiber of the filter media. Bicomponent fiber can be used toform a fiber layer. During layer formation, a liquid resin can be used.In the resin saturation process of the media, the liquid binding resincan migrate to the outer sides of the filter media making the internalfibers of the media unbonded relatively. During the pleating process,the unbonded regions cause degrading media stiffness and durability andexcessive manufacturing scrap. Bicomponent and homopolymer binder fiberswere used in this invention to enhance the internal bonding betweenfiber and fiber of the filter media. Bicomponent fibers are coextrudedwith two different polymers in the cross section; they can be concentricsheath/core, eccentric sheath/core or side-by-side, etc.

The bicomponent fibers used in this work are concentric sheath/core:

TJ04CN Teijin Ltd. (Japan) 2.2 DTEX×5 mm sheath core PET/PET

3380 Unitika Ltd. (Japan) 4.4 DTEX×5 mm sheath core PET/PET

The homopolymer binder fiber 3300 sticks at 130° C. and has thedimension of 6.6 DTEX×5 mm. The sheath melting temperatures of TJ04CNand 3380 are at 130° C.; and the core melting temperatures of thesebinder fibers are at 250° C. Upon heating, the sheath fiber componentbegins to melt and spread out, attaching itself in the fiber matrix; andthe core fiber component remains in the media and functions to improvethe media strength and flexibility. Unpressed handsheets were made inthe Corporate Media Lab at Donaldson. Also pressed handsheets were madeand pressed at 150° C. (302° F.) for 1 minute. In the Description of theInvention, some codes and furnish percentages of the handsheets and theinternal bond strength test results will be presented. Results show thatthe Teijin and Unitika binder fibers would improve internal bondstrengths in the synthetic media.

Eight furnish formulations were created in this work. Below are theinformation about the furnish formulations. Johns Manville 108B andEvanite 710 are glass fibers. Teijin TJ04CN, Unitika 3380, and Unitika3300 are binder fibers. Polyester LS Code 6 3025-LS is made byMiniFibers, Inc.

Furnish Fibers % of Furnish Weight (g) Example 1 Johns Manville 108B 401.48 Unitika 3300 17.5 0.6475 Polyester LS Code 6 3025-LS 42.5 1.5725Example 2 Evanite 710 40 1.48 Unitika 3300 10 0.37 Polyester LS Code 63025-LS 50 1.85 Example 3 Evanite 710 40 1.48 Unitika 3300 15 0.555Polyester LS Code 6 3025-LS 45 1.665 Example 4 Evanite 710 40 1.48Unitika 3300 17.5 0.6475 Polyester LS Code 6 3025-LS 42.5 1.5725 Example5 Evanite 710 40 1.48 Unitika 3300 20 0.74 Polyester LS Code 6 3025-LS40 1.48 Example 6 Evanite 710 40 1.48 Polyester LS Code 6 3025-LS 602.22 Example 7 Evanite 710 40 1.48 Teijin TJ04CN 17.5 0.6475 PolyesterLS Code 6 3025-LS 42.5 1.5725 Example 8 Evanite 710 40 1.48 Unitika 338017.5 0.6475 Polyester LS Code 6 3025-LS 42.5 1.5725

The handsheet procedure includes an initial weigh out of the individualfibers. About six drops of Emerhurst 2348 was placed into a 100 mls. ofwater and set aside. About 2 gallons of cold clean tap water was placedinto a 5 gallon container with 3 mls. of the Emerhurst solution andmixed. The synthetic fibers were added and allowed to mix for at least 5minutes before adding additional fibers. Fill the Waring blender withwater ½ to ¾ full, add 3 mls. of 70% sulfuric acid. Add the glassfibers. Mix on the slowest speed for 30 seconds. Add to the syntheticfibers in the pail. Mix for an additional 5 minutes. Add the binderfibers to the container. Clean and rinse the dropbox out prior to using.Insert handsheet screen and fill to the first stop. Remove air trappedunder the screen by jerking up on the plunger. Add the furnish to thedropbox, mix with the plunger, and drain. Vacuum of the handsheet withthe vacuum slot. If no pressing is required, remove the handsheet fromthe screen and dry at 250.

Pressed Handsheets at 100 psi

Below are the physical data of the pressed handsheets that were madeduring Sep. 1, 2005 to Sep. 14, 2005 based on the above furnishformulations. The handsheets were pressed at 100 psi.

Example Example Example Example Sample ID 1 2 #1 2 #2 3 #1 BW (g) 3.523.55 3.58 3.55 (8 × 8 sample) Thickness (inch) 0.019 0.022 0.023 0.022Perm (cfm) 51.1 93.4 90.3 85.8 Internal Bond 56.5 25.8 26.4 39 ExampleExample Example Example Sample ID 3 #2 4 #1 4 #2 5 #1 BW (g) 3.54 3.413.45 3.6 (8 × 8 sample) Thickness (inch) 0.02 0.017 0.018 0.022 Perm(cfm) 81.3 59.4 64.1 93.1 Internal Bond 46.2 40.6 48.3 42.2 ExampleExample Example Example Sample ID 5 #2 6 #1 6 #2 7 #1 BW (g) 3.51 3.563.56 3.63 (8 × 8 sample) Thickness (inch) 0.021 0.021 0.02 0.021 Perm(cfm) 89.4 109.8 108.3 78.9 Internal Bond 49.4 3.67 No Value 28.2Example Example Example Sample ID 7 #2 8 #1 8 #2 BW (g) 3.54 3.41 3.45(8 × 8 sample) Thickness (inch) 0.02 0.017 0.018 Perm (cfm) 81.3 59.464.1 Internal Bond 46.2 40.6 48.3

Handsheet without having Unitika 3300 were made. Results from Examples 6#1 and 6 #2 showed that the handsheets without having Unitika 3300 hadpoor internal bond strengths.

The internal bond data show that the bond strengths will be at optimumwith the presence of 15%-20% of Unitika 3300 in the furnish.

Results from Examples 4 #1, 4 #2, 7 #1, 7 #2, 8 #1, and 8 #2 show thatUnitika 3300 works better than Teijin TJ04CN and Unitika 3380 increating internal bond strengths in the handsheets.

More Useful Preferred Preferred Basis Wt. (g) 3 to 4 3.2 to 3.6 3.3 to3.3 (8″ × 8″ sample) Thickness (in) 0.02 0.017 0.018 Perm (cfm) 81.359.4 64.1 Internal Bond 46.2 40.6 48.3

Unpressed Handsheets

Two handsheet Samples 4 #3 and 4 #4 were made without pressed. Afterbeing dried in the photodrier; the samples were put in the oven for 5minutes at 300° F.

Sample ID Example 4 #3 Example 4 #4 BW (g) 3.53 3.58 (8″ × 8″ sample)Thickness (inch) 0.029 0.03 Perm (cfm) 119.8 115.3 Internal Bond 17.819.8

Compared to Samples 4 #1 and 4 #2 (pressed handsheet), the unpressedsamples 4 #3 and 4 #4 were having much lower internal bond strengths.

Pressed Handsheets at 50 psi

Two handsheet Samples 4 #5 and 4 #6 were made and pressed at 50 psi.Below are the physical properties of the handsheets.

Sample ID Example 4 #5 Example 4 #6 BW (g) 3.63 3.65 (8″ × 8″ sample)Thickness (inch) 0.024 0.023 Perm (cfm) 91.4 85.8 Internal Bond 33.5 46

Results of Examples 4 #1-4 #6 show that binders are more effective withpressing.

Pressed and Saturated Handsheets

Two handsheet Examples 4 #7 and 6 #3 were made. First, the handsheetswere dried in the photodrier; then were saturated in the solution of 95%Rhoplex TR-407 (Rohm & Haas) and 5% Cymel 481 (Cytec) on dry resinbasis. Then the handsheets were pressed at 100 psi and tested. Below arethe physical properties of the saturated handsheets. Results show thatthe resin solution may decrease the internal bond strengths

Sample ID Example 4 #7 Example 6 #3 BW (g) 3.57 3.65 (8″ × 8″ sample)Final BW (g) 4.43 4.62 (8″ × 8″ sample) Pick-up percent (%) 24.1 26.6Thickness (inch) 0.019 0.022 Perm (cfm) 64.9 67.4 Internal Bond 32.3 NoValue

Results show that the Teijin TJ04CN, Unitika 3380 and Unitika 3300binder fibers would improve internal bond strengths in the syntheticmedia and Unitika 3300 works best among the binder fibers. Handsheetswithout having Unitika 3300 had poor internal bond strengths. Handsheetswere having optimum bond strengths with the presence of 15%-20% ofUnitika 3300 in the furnish. Pressed handsheets were having higherinternal bond strengths than unpressed handsheets. The latex resin doesnot provide internal bond strengths to polyester fibers. Latex resin maybe used in conjunction with the binder fibers but the binder fiberswould yield more effective internal bond strengths without latex resin.

The sheet media of the invention are typically made using papermakingprocesses. Such wet laid processes are particularly useful and many ofthe fiber components are designed for aqueous dispersion processing.However, the media of the invention can be made by air laid processesthat use similar components adapted for air laid processing. Themachines used in wet laid sheet making include hand laid sheetequipment, Fourdrinier papermaking machines, cylindrical papermakingmachines, inclined papermaking machines, combination papermakingmachines and other machines that can take a properly mixed paper, form alayer or layers of the furnish components, remove the fluid aqueouscomponents to form a wet sheet. A fiber slurry containing the materialsare typically mixed to form a relatively uniform fiber slurry. The fiberslurry is then subjected to a wet laid papermaking process. Once theslurry is formed into a wet laid sheet, the wet laid sheet can then bedried, cured or otherwise processed to form a dry permeable, but realsheet, media, or filter. Once sufficiently dried and processed tofiltration media, the sheets are typically about 0.25 to 1.9 millimeterin thickness, having a basis weight of about 20 to 200 or 30 to 150g-m⁻². For a commercial scale process, the bicomponent mats of theinvention are generally processed through the use of papermaking-typemachines such as commercially available Fourdrinier, wire cylinder,Stevens Former, Roto Former, Inver Former, Venti Former, and inclinedDelta Former machines. Preferably, an inclined Delta Former machine isutilized. A bicomponent mat of the invention can be prepared by formingpulp and glass fiber slurries and combining the slurries in mixingtanks, for example. The amount of water used in the process may varydepending upon the size of the equipment used. The furnish may be passedinto a conventional head box where it is dewatered and deposited onto amoving wire screen where it is dewatered by suction or vacuum to form anon-woven bicomponent web. The web can then be coated with a binder byconventional means, e.g., by a flood and extract method and passedthrough a drying section which dries the mat and cures the binder, andthermally bonds the sheet, media, or filter. The resulting mat may becollected in a large roll.

The medium or media can be formed into substantially planar sheets orformed into a variety of geometric shapes using forms to hold the wetcomposition during thermal bonding. The media fiber of the inventionincludes glass, metal, silica, polymer and other related fibers. Informing shaped media, each layer or filter is formed by dispersingfibers in an aqueous system, and forming the filter on a mandrel withthe aid of a vacuum. The formed structure is then dried and bonded in anoven. By using a slurry to form the filter, this process provides theflexibility to form several structures; such as, tubular, conical, andoval cylinders.

Certain preferred arrangements according to the present inventioninclude filter media as generally defined, in an overall filterconstruction. Some preferred arrangements for such use comprise themedia arranged in a cylindrical, pleated configuration with the pleatsextending generally longitudinally, i.e. in the same direction as alongitudinal axis of the cylindrical pattern. For such arrangements, themedia may be imbedded in end caps, as with conventional filters. Sucharrangements may include upstream liners and downstream liners ifdesired, for typical conventional purposes. Permeability relates to thequantity of air (ft³-min⁻¹-ft⁻² or ft-min⁻¹) that will flow through afilter medium at a pressure drop of 0.5 inches of water. In general,permeability, as the term is used is assessed by the FrazierPermeability Test according to ASTM D737 using a Frazier PermeabilityTester available from Frazier Precision Instrument Co. Inc.,Gaithersburg, Md. or a TexTest 3300 or TexTest 3310 available fromTexTest 3300 or TexTest 3310 available from Advanced Testing InstrumentsCorp (ATI), 243 East Black Stock Rd. Suite 2, Spartanburg, S.C. 29301,(864)989-0566, www.aticorporation.com. Pore size referred to in thisdisclosure means mean flow pore diameter determined using a capillaryflow porometer instrument like Model APP 1200 AEXSC sold by PorusMaterials, Inc., Cornell University Research Park, Bldg. 4.83 BrownRoad, Ithaca, new York 14850-1298, 1-800-825-5764, www.pmiapp.com.

Preferred crankcase ventilation filters of the type characterized hereininclude at least one media stage comprising wet laid media. The wet laidmedia is formed in a sheet form using wet laid processing, and is thenpositioned on/in the filter cartridge. Typically the wet laid mediasheet is at least used as a media stage stacked, wrapped or coiled,usually in multiple layers, for example in a tubular form, in aserviceable cartridge. In use, the serviceable cartridge would bepositioned with the media stage oriented for convenient drainagevertically. For example, if the media is in a tubular form, the mediawould typically be oriented with a central longitudinal axis extendinggenerally vertically.

As indicated, multiple layers, from multiple wrappings or coiling, canbe used. A gradient can be provided in a media stage, by first applyingone or more layers of wet laid media of first type and then applying oneor more layers of a media (typically a wet laid media) of a different,second, type. Typically when a gradient is provided, the gradientinvolves use of two media types which are selected for differences inefficiency. This is discussed further below.

Herein, it is important to distinguish between the definition of themedia sheet used to form the media stage, and the definitions of theoverall media stage itself. Herein the term “wet laid sheet,” “mediasheet” or variants thereof, is used to refer to the sheet material thatis used to form the media stage in a filter, as opposed to the overalldefinition of the total media stage in the filter. This will be apparentfrom certain of the following descriptions.

Secondly, it is important to understand that a media stage can beprimarily for coalescing/drainage, for both coalescing/drainage andparticulate filtration, or primarily for particulate filtration. Mediastages of the type of primary concern herein, are at least used forcoalescing/drainage, although they typically also have particulateremoval function and may comprise a portion of an overall media stagethat provides for both coalescing/drainage and desired efficiency ofsolid particulate removal.

In the example arrangement described above, an optional first stage anda second stage were described in the depicted arrangements. Wet laidmedia according to the present descriptions can be utilized in eitherstage. However typically the media would be utilized in a stage whichforms, in the arrangements shown, the tubular media stages. In someinstances when materials according to the present disclosure are used,the first stage of media, characterized as the optional first stagehereinabove in connection with the figures, can be avoided entirely, toadvantage.

The media composition of the wet laid sheets used to form a stage in afilter is provided in a form having a calculated pore size (X-Ydirection) of at least 10 micron, usually at least 12 micron. The poresize is typically no greater than 60 micron, for example within therange of 12-50 micron, typically 15-45 micron. The media is formulatedto have a DOP % efficiency (at 10.5 fpm for 0.3 micron particles),within the range of 3-18%, typically 5-15%. The media can comprise atleast 30% by weight, typically at least 40% by weight, often at least45% by weight and usually within the range of 45-70% by weight, based ontotal weight of filter material within the sheet, bi-component fibermaterial in accord with the general description provided herein. Themedia comprises 30 to 70% (typically 30-55%), by weight, based on totalweight of fiber material within the sheet, of secondary fiber materialhaving average largest cross-sectional dimensions (average diameters isround) of at least 1 micron, for example within the range of 1 to 20micron. In some instances it will be 8-15 micron. The average lengthsare typically 1 to 20 mm, often 1-10 mm, as defined. This secondaryfiber material can be a mix of fibers. Typically polyester and/or glassfibers are used, although alternatives are possible. Typically andpreferably the fiber sheet (and resulting media stage) includes no addedbinder other than the binder material contained within the bi-componentfibers. If an added resin or binder is present, preferably it is presentat no more than about 7% by weight of the total fiber weight, and morepreferably no more than 3% by weight of the total fiber weight.Typically and preferably the wet laid media is made to a basis weight ofat least 20 lbs. per 3,000 square feet (9 kg/278.7 sq. m.), andtypically not more than 120 lbs. per 3,000 square feet (54.5 kg/278.7sq. m.). Usually it will be selected within the range of 40-100 lbs. per3,000 sq. ft. (18 kg-45.4 kg/278.7 sq. m). Typically and preferably thewet laid media is made to a Frazier permeability (feet per minute) of40-500 feet per minute (12-153 meters/min.), typically 100 feet perminute (30 meters/min.). For the basis weights on the order of about 40lbs/3,000 square feet-100 lbs./3,000 square feet (18-45.4 kg/278.7 sq.meters), typical permeabilities would be about 200-400 feet per minute(60-120 meters/min.). The thickness of the wet laid media sheet(s) usedto later form the described media stage in the filter at 0.125 psi (8.6millibars) will typically be at least 0.01 inches (0.25 mm) often on theorder of about 0.018 inch to 0.06 inch (0.45-1.53 mm); typically0.018-0.03 inch (0.45-0.76 mm).

Media in accord with the general definitions provided herein, includinga mix of bi-component fiber and other fiber, can be used as any mediastage in a filter as generally described above in connection with thefigures. Typically and preferably it will be utilized to form thetubular stage. When used in this manner, it will typically be wrappedaround a center core of the filter structure, in multiple layers, forexample often at least 20 layers, and typically 20-70 layers, althoughalternatives are possible. Typically the total depth of the wrappingwill be about 0.25-2 inches (6-51 mm), usually 0.5-1.5 (12.7-38.1 mm)inches depending on the overall efficiency desired. The overallefficiency can be calculated based upon the number of layers and theefficiency of each layer. For example the efficiency at 10.5 feet perminute (3.2 m/min) for 0.3 micron DOP particles for media stagecomprising two layers of wet laid media each having an efficiency of 12%would be 22.6%, i.e., 12%+0.12×88.

Typically enough media sheets would be used in the final media stage toprovide the media stage with overall efficiency measured in this way ofat least 85%, typically 90% or greater. In some instances it would bepreferred to have the efficiency at 95% or more. In the context the term“final media stage” refers to a stage resulting from wraps or coils ofthe sheet(s) of wet laid media.

In crankcase ventilation filters, a calculated pore size within therange of 12 to 80 micron is generally useful. Typically the pore size iswithin the range of 15 to 45 micron. Often the portion of the mediawhich first receives gas flow with entrained liquid for designscharacterized in the drawings, the portion adjacent the inner surface oftubular media construction, through a depth of at least 0.25 inch (6.4mm), has an average pore size of at least 20 microns. This is because inthis region, a larger first percentage of the coalescing/drainage willoccur. In outer layers, in which less coalescing drainage occur, asmaller pore size for more efficient filtering of solid particles, maybe desirable in some instances. The term X-Y pore size and variantsthereof when used herein, is meant to refer to the theoretical distancebetween fibers in a filtration media. X-Y refers to the surfacedirection versus the Z direction which is the media thickness. Thecalculation assumes that all the fibers in the media are lined parallelto the surface of the media, equally spaced, and ordered as a squarewhen viewed in cross-section perpendicular to the length of the fibers.The X-Y pore size is a distance between the fiber surface on theopposite corners of the square. If the media is composed of fibers ofvarious diameters, the d² mean of the fiber is used as the diameter. Thed² mean is the square root of the average of the diameters squared. Ithas been found that it is useful to have calculated pore sizes on thehigher end of the preferred range, typically 30 to 50 micron, when themedia stage at issue has a total vertical height, in the crankcaseventilation filter of less than 7 inches (178 mm); and, pore sizes onthe smaller end, about 15 to 30 micron, are sometimes useful when thefilter cartridge has a height on the larger end, typically 7-12 inches(178-305 mm). A reason for this is that taller filter stages provide fora higher liquid head, during coalescing, which can force coalescedliquid flow, under gravity, downwardly through smaller pores, duringdrainage. The smaller pores, of course, allow for higher efficiency andfewer layers. Of course in a typical operation in which the same mediastage is being constructed for use in a variety of filter sizes,typically for at least a portion of the wet laid media used for thecoalescing/drainage in initial separation, an average pore size of about30-50 microns will be useful.

Solidity is the volume fraction of media occupied by the fibers. It isthe ratio of the fibers volume per unit mass divided by the media'svolume per unit mass. Typical wet laid materials preferred for use inmedia stages according to the present disclosure, especially as thetubular media stage in arrangements such as those described above inconnection with the figures, have a percent solidity at 0.125 psi (8.6millibars) of under 10%, and typically under 8%, for example 6-7%. Thethickness of media utilized to make media packs according to the presentdisclosure, is typically measured using a dial comparator such as anAmes #3W (BCA Melrose MA) equipped with a round pressure foot, onesquare inch. A total of 2 ounces (56.7 g) of weight is applied acrossthe pressure foot. Typical wet laid media sheets useable to be wrappedor stacked to form media arrangements according to the presentdisclosure, have a thickness of at least 0.01 inches (0.25 mm) at 0.125psi (8.6 millibars), up to about 0.06 inches (1.53 mm), again at 0.125psi (8.6 millibars). Usually, the thickness will be 0.018-0.03 inch(0.44-0.76 mm) under similar conditions.

Compressibility is a comparison of two thickness measurements made usingthe dial comparator, with compressibility being the relative loss ofthickness from a 2 ounce (56.7 g) to a 9 ounce (255.2 g) total weight(0.125 psi-0.563 psi or 8.6 millibars-38.8 millibars). Typical wet laidmedia (at about 40 lbs/3,000 square feet (18 kg/278.7 sq. m) basisweight) useable in wrappings according to the present disclosure,exhibit a compressibility (percent change from 0.125 psi to 0.563 psi or8.6 millibars-38.8 millibars) of no greater than 25%, and typically12-16%.

The media of the invention have a preferred DOP efficiency at 10.5ft/minute for 0.3 micron particles for layers or sheets of wet laidmedia. This requirement indicates that a number of layers of the wetlaid media will typically be required, in order to generate an overalldesirable efficiency for the media stage of typically at least 85% oroften 90% or greater, in some instances 95% or greater. In general, DOPefficiency is a fractional efficiency of a 0.3 micron DOP particle(dioctyl phthalate) challenging the media at 10 fpm. A TSI model 3160Bench (TSI Incorporated, St. Paul, Minn.) can be used to evaluate thisproperty. Model dispersed particles of DOP are sized and neutralizedprior to challenging the media. The wet laid filtration mediaaccomplishes strength through utilization of added binders. However thiscomprises the efficiency and permeability, and increases solidity. Thus,as indicated above, the wet laid media sheets and stages according topreferred definitions herein typically include no added binders, or ifbinder is present it is at a level of no greater than 7% of total fiberweight, typically no greater than 3% of total fiber weight. Fourstrength properties generally define media gradings: stiffness, tensile,resistance to compression and tensile after fold. In general,utilization of bi-component fibers and avoidance of polymeric bindersleads to a lower stiffness with a given or similar resistance tocompression and also to good tensile and tensile after fold. Tensilestrength after folding is important, for media handling and preparationof filter cartridges of the type used in many crankcase ventilationfilters. Machine direction tensile is the breaking strength of a thinstrip of media evaluated in the machine direction (MD). Reference is toTappi 494. Machine direction tensile after fold is conducted afterfolding a sample 180° relative to the machine direction. Tensile is afunction of test conditions as follows: sample width, 1 inch (25.4 mm);sample length, 4 inch gap (101.6 mm); fold—1 inch (25.4 mm) wide sample180° over a 0.125 inch (3.2 mm) diameter rod, remove the rod and place a10 lb. weight (4.54 kg) on the sample for 5 minutes. Evaluate tensile;pull rate—2 inches/minute (50.8 mm/minute).

Example 9

Example 9, EX1051, is a sheet material useable for example, as a mediaphase in a filter and can be used in layers to provide useableefficiencies of overall filtration. The material will drain well andeffectively, for example when used as a tubular media constructionhaving a height of 4 inches-12 inches (100-300.5 mm). The media can beprovided in multiple wrappings, to generate such a media pack. The mediacomprises a wet laid sheet made from a fiber mix as follows: 50% by wt.DuPont polyester bi-component 271P cut to 6 mm length; 40% by wt. DuPontpolyester 205 WSD, cut to 6 mm length; and 10% by wt. Owens CorningDS-9501-11W Advantex glass fibers, cut to 6 mm. The DuPont 271Pbi-component fiber is an average fiber diameter of about 14 microns. TheDuPont polyester 205 WSD fiber has an average fiber diameter of about12.4 microns. The Owens Corning DS-9501-11W has an average fiberdiameter of about 11 microns. The material was made to a basis weight ofabout 40.4 lbs./3,000 sq. ft. The material had a thickness at 0.125 psi,of 0.027 inches and at 0.563 psi of 0.023 inches. Thus, the totalpercent change (compressibility) from 0.125 to 0.563 psi, was only 14%.At 1.5 psi, the thickness of the material was 0.021 inches. The solidityof the material at 0.125 psi was 6.7%. The permeability (frazier) was392 feet per minute. The MD fold tensile was 2.6 lbs./inch width. Thecalculated pore size, X-Y direction, was 43 microns. The DOP efficiencyof 10.5 feet per minute per 0.43 micron particles, was 6%.

Example 10

Example 10, EX1050, was made from a fiber mixture comprising 50% byweight DuPont polyester bi-component 271P cut to 6 mm length; and 50% byweight Lauscha B50R microfiber glass. The microfiber glass had lengthson the order of about 3-6 mm. Again, the DuPont polyester bi-component271P had an average diameter of 14 microns. The Lauscha B50R had anaverage diameter of 1.6 microns and a d² mean of 2.6 microns.

The sample was made to a basis weight of 38.3 lbs./3,000 square feet.The thickness of the media at 0.125 psi, 0.020 inches and at 0.563 psiwas 0.017 inches. Thus the percent changed from 0.125 psi to 0.563 psiwas 15%, i.e., 15% compressibility. At 1.5 psi, the sample had athickness of 0.016 inches. The solidity of the material measured at0.125 psi was 6.9%. The permeability of the material was about 204feet/minute. The machine direction fold tensile was measured at 3.9lbs/inch width. The calculated pore size X-Y direction was 18 microns.The DOP efficiency at 10.5 ft/minute for 0.3 micron particles, was 12%.The material would be effective when used as a layer or a plurality oflayers to polish filtering. Because of its higher efficiency, it can beused alone or in multiple layers to generate high efficiency in themedia.

Example 11

Example 11, EX 1221, is a sheet material useable for example, as a mediaphase in a filter and can be used in layers to provide usableefficiencies for overall filtration. The material will not drain as wellas either example 9 or 10 but will exhibit much higher efficiency. It isuseful for mist applications where load rate is lower and elementconstruction allows for a pleated construction of higher pleat height,such as 10 inches. The media was made from a fiber mixture comprising50% by weight DuPont polyester bi-component 271P cut to 6 mm length; and12.5% by weight Lauscha B50R microfiber glass and 37.5% Lauscha B26R.The microfiber glass had lengths on the order of about 3-6 mm. Again,the DuPont polyester bi-component 271P had an average diameter of 14microns. The Lauscha B50R had an average diameter of 1.6 microns and ad² mean of 2.6 microns.

The sample was made to a basis weight of 78.8 lbs./3,000 square feet.The thickness of the media at 0.125 psi, 0.050 inches and at 0.563 psiwas 0.039 inches. Thus the percent changed from 0.125 psi to 0.563 psiwas 22%, i.e., 22% compressibility. At 1.5 psi, the sample had athickness of 0.035 inches. The solidity of the material measured at0.125 psi was 5.6%. The permeability of the material was about 68feet/minute. The machine direction fold tensile was measured at 6.8lbs/inch width. The calculated pore size X-Y direction was 16 microns.The DOP efficiency at 10.5 ft/minute for 0.3 micron particles, was 26%.The material would be effective when used as a layer or a plurality oflayers to polish filtering. Because of its higher efficiency, it can beused alone or in multiple layers to generate high efficiency in themedia.

Increased hydrophilic modification of the surface characteristics of thefibers in media, such as increasing the contact angle, should enhancewater binding and the drainage capability of the filtration media andthus the performance of a filter (reduced pressure drop and improvedmass efficiency). Various fibers are used in the design of for examplefiltration media used for low pressure filters such as mist filters orothers (less than 1 psi terminal pressure drop). One method of modifyingthe surface of the fibers is to apply a surface treatment such as afluorochemical or silicone containing material, 0.001 to 5% or about0.01 to 2% by weight of the media. We anticipate modifying the surfacecharacteristics of the fibers in a wet laid layer that can includebicomponent fibers, other secondary fiber such as a synthetic, ceramicor metal fibers with and without additional resin binder at about 0.001to 7% by weight when used. The resulting media would be incorporatedinto filter element structures with a thickness generally greater than0.05 inches often about 0.1 to 0.25 inches. The media would have largerXY pore size than conventional air media, generally greater than 10often about 15 to 100 micron, and would be composed of larger sizefibers, generally greater than 6 micron although in certain cases smallfibers could be used to enhance efficiency. The use of surface modifiersshould allow the construction of media with smaller XY pore sizes thanuntreated media, thereby increasing efficiency with the use of smallfibers, reduce the thickness of the media for more compact elements, andreduce the equilibrium pressure drop of the element.

In the case of mist filtration, the system must be designed to drain thecollected liquids; otherwise element life is uneconomically short. Mediain both prefilter and primary element are positioned so that the liquidcan drain from the media. The primary performance properties for thesetwo elements are: initial and equilibrium fractional efficiency,pressure drop, and drainage ability. The primary physical properties ofthe media are thickness, solidity, and strength.

The elements are typically aligned vertically which enhances thefilter's capability to drain. In this orientation, any given mediacomposition will exhibit a equilibrium liquid height which will be afunction of the XY pore size, fiber orientation, and the interaction ofthe liquid with the fibers' surface, measured as contact angle. Thecollection of liquid in the media will increase the height to a pointbalanced with the drainage rate of liquid from the media. Any portion ofthe media that is plugged with draining liquid would not be availablefor filtration thus increasing pressure drop and decreasing efficiencyacross the filter. Thus it is advantageous to minimize the portion ofthe element that retains liquid.

The three media factors effecting drainage rate, XY pore size, fiberorientation, and interaction of the liquid being drained with thefiber's surface, can all be modified to minimize the portion of themedia that is plugged with liquid. The XY pore size of the element canbe increased to enhance the drainage capability of the media but thisapproach has the effect of reducing the number of fibers available forfiltration and thus the efficiency of the filter. To achieve targetefficiency, a relatively thick element structure may be needed,typically greater than 0.125 inches, due to the need for a relativelylarge XY pore size. The fibers can be oriented with the verticaldirection of the media but this approach is difficult to achieve in amanufacturing scenario. The interaction of the liquid being drained withthe surface of the fibers can be modified to enhance the drainage rate.This invention disclosure supports this approach.

In one application, crank case filtration applications, small oilparticle mists are captured, collect in the element and eventually drainfrom the element back into the engine's oil sump. Filtration systemsinstalled on the crank case breather of diesel engines can be composedof multiple elements, a pre filter that removes large particlesgenerally greater than 5 microns and a primary filter that removes thebulk of the residual contamination. The primary element can be composedof single or multiple layers of media. The composition of each layer canbe varied to optimize efficiency, pressure drop and drainageperformance.

Due to filtration system size constraints, the pre and primary elementsmust be designed for equilibrium fractional efficiency. Equilibriumfractional efficiency is defined as the element's efficiency once theelement is draining liquid at a rate equal to the collection rate. Thethree performance properties, initial and equilibrium fractionalefficiency, pressure drop, and drainage ability, are balanced againstthe element's design to achieve optimum performance. Thus, as anexample, short elements in a high liquid loading environment must bedesigned to drain at a relatively fast rate.

Filtration performance (relative low pressure drop, high efficiency andthe capability to drain) coupled with space requirements necessitatesshort elements composed of relatively thick, open media. As an examplethe small Spiracle element would be a vertically positioned cylinder offiltration media with an ID of 2″ and thickness of 0.81 inches. Theheight of the media available for filtration would be only 4.72″.

Various element configurations are being evaluated. The pre filter iscomposed of two layers of dry laid high loft polyester media. Theprimary element is composed of multiple wraps of EX 1051, 42 to 64layers dependent on the available OD dimensions. Structures such as 32wraps of EX 1051 and 12 wraps of EX 1050 separated with expanded metalhave been evaluated. Various basis weights can be used to achieveequivalent element thickness. The elements are being tested in standardengine blow-by filter housings, reverse flow (cylindrical elements withthe flow from the inside-out). Modifications to the housings areanticipated to enhance oil drainage. It is also envisioned that theprimary element could be an inner wrap. Other pre and primary elementmedia configurations are anticipated such as dry laid VTF, use of otherdry laid media grades utilizing bicomponent fibers or other combinationsof fibers using the wet laid process.

This same approach can be used in applications where height restrictionsare not as stringent but the drainage rate of the media is of primaryconcern. As an example, Industrial Air Filtration utilizes mediacollecting mist particles generated from the cooling fluids used inmachine tool cutting. In this case the height of the media positioned inthe vertical direction is 10 inches to greater than 30 inches. Thus asmaller XY pore size can be used but enhanced drainage will improve theperformance of the element, equilibrium efficiency and pressure drop. Wehave evaluated a second media grade. The media grade, EX 1050, iscomposed of 50% by mass DuPont Polyester bicomponent 271P cut 6 mm and50% by mass Lauscha B50R microfiber glass (see attached mediaphysicals). Additional grades of media incorporating small microfiberglass have been evaluated.

It is anticipated that some combination of fiber size, solidityresulting in an XY pore size coupled with surface modification willyield superior performance where as a much smaller XY pore size willyield inferior performance.

The media's performance was evaluated in element form. Multiple wraps ofEX 1051-40 media, approximately 42, were wound around a center core. Twolayers of a pre filter, EN 0701287, a dry laid latex impregnated mediacomposed of large polyester fibers and large pores were cut out as acircle and placed on one end of the center core. Both ends were pottedand the element was positioned in a housing so that challenge air wasdirected through the prefilter then into the inside of the wrapped coreand through the media to the outside of the cylinder.

Challenge oil, Mallinckrodt N.F. 6358 mineral oil, is created usingeither a Laskin and/or TSI atomizer. Both the number of nozzles and airpressure is varied to generate particles and maintain mass flow. A 2/1mass ratio between the Laskin and TSI atomizers is produced to evaluatesmall and medium size CCV elements. Both nozzles are used to matchexpected particle distributions exhibited in diesel engine crank caseventilation.

The element evaluations were initiated at the high/high test conditionwithout any presoaking, to model worse case field conditions. Every 24hours of operation a mass balance is conducted to determine elementefficiency. The flow and oil feed rate condition is maintained until theelement has achieved equilibrium, defined when the mass of oil drainedequals the mass of oil captured (>95% of equilibrium). A pressuredrop/flow curve is then obtained by obtaining DP at various flows.

Under low flow and flux (2 cfm and 7.4 gm/hr/sq ft), the equilibriumpressure drop for a small size diesel engine crank case ventilationelement (ID: 2 inches of water, OD: 3.62″ media height 5.25″) utilizinguntreated EX 1051-40 media (˜42 wraps of 40 lb/3,000 sq ft) was 1.9″ ofwater. Equilibrium mass efficiency of 92.7%. A media treated withapproximately 2.5% Zonly 7040, a fluorochemical, and used to constructan equivalent element exhibited an equilibrium pressure drop of 2.7″ ofwater but a mass efficiency of 98.8%.

Wet Laid Mist Media Com- press- ability 3160 % DOP change Solidity MDCalculated Efficiency Basis Thickness from at Fold Pore Size, @ 10.5Fiber size, Weight inches, inches, inches, 0.125 oz 0.125 Tensile X-Yfpm average lb/3000 0.125 0.563 1.5 to 0.563 psi Perm lb/in direction %at Units Composition diameter sq ft psi psi psi psi % fpm width microns0.3 um Example 50% by mass DuPont 271P: 38.3 0.020 0.017 0.016 15 6.9204 3.9 18 12.0 10, Polyester bicomponent 14 microns, 271P cut 6 mm, 50%by B50R: mass Lauscha B50R 1.6 microns microfiber glass (2.5 um d² mean)Example 50% by mass DuPont 271P: 40.4 0.027 0.023 0.021 14 6.7 392 2.643 6.0 9 Polyester bicomponent 14 microns, 271P cut 6 mm, 40% by 205WSD: mass DuPont Polyester 12.4 microns 205 WSD cut 6 mm, DS-9501- 10%by mass Owens 11W: Corning DS-9501-11W 11 microns Advantex cut to 6 mmExample 50% by mass DuPont 271P: 78.8 0.050 0.039 0.035 22 5.6 68 6.9 1626.3 11 Polyester bicomponent 14 microns, 271P cut 6 mm, 12.5% B50R: bymass Lauscha B50R 1.6 microns microfiber glass and (2.5 um 37.5% by massLauscha d² mean) B26R B26R: 1.5 micron (1.95) Range 20 to 120 Produced

In one embodiment of the invention, the filtration medium or media iscomprised of a thermally bonded sheet. The sheet is comprised of about20 to 80 wt % of a bicomponent binder fiber and about 20 to 80 wt % of aglass fiber. The bicomponent binder fiber has a diameter of about 5 to50 micrometers and a length of about 0.1 to 15 cm. The glass fiber has adiameter of about 0.1 to 30 micrometers and an aspect ratio of about 10to 10,000. The media has a thickness of about 0.2 to 50 mm, a solidityof about 2 to 25%, a basis weight of about 10 to 1000 g-m-2, a pore sizeof about 0.5 to 100 micrometers and a permeability of about 5 to 500ft-min-1. The media is comprised of about 0.1 to 10 wt % of a binderresin. The media is comprised of about 0.5 to 15 wt % of a secondaryfiber. One example of the secondary fiber would be a glass fiber whereinthe glass fiber is selected from one or two or more sources of glassfiber where the average diameter of the glass fiber is of about 0.1 to 1micrometers, 0.3 to 2 micrometers, 0.5 to 5 micrometers, 0.75 to 7micrometers, 1 to 10 micrometers, or 3 to 30 micrometers. The media iscomprised of a single layer or two or more layers. The media iscomprised of about 0.01 to 10 wt % of a fluoro-organic agent.

In one embodiment of the invention, the invention is a liquid filtrationmedium comprised of a thermally bonded sheet. The thermally bonded sheetis comprised of about 10 to 90 wt % of a bicomponent binder fiber andabout 10 to 90 wt % of a media fiber. The bicomponent binder fiber has adiameter of about 5 to 50 micrometers and a length of about 0.1 to 15cm. The media fiber has a diameter of about 0.1 to 5 micrometers and anaspect ratio of about 10 to 10,000. The media has a thickness of about0.1 to 2 mm, a solidity of about 2 to 25%, a basis weight of about 2 to200 g-m-2, a pore size of about 0.2 to 50 micrometers and a permeabilityof about 2 to 200 ft-min-1. The media fiber is comprised of a secondaryfiber. The media fiber is comprised of a glass fiber. The glass fiber isselected from one or two or more sources of glass fiber where theaverage diameter of the glass fiber is of about 0.1 to 1 micrometers,0.3 to 2 micrometers, 0.5 to 5 micrometers, 0.75 to 7 micrometers, 1 to10 micrometers, or 10 to 50 micrometers. The media is comprised of about0.1 to 25 wt % of a binder resin. The media is comprised of a singlelayer or two or more layers. The media is comprised of about 0.01 to 10wt % of a fluoro-organic agent.

A method of the invention embodies filtering a liquid stream, where themethod is comprised of placing a filter unit into the stream andretaining particulate entrained in the filter in the stream using filtermedia within the filter unit. The filter media is comprised of athermally bonded sheet. The thermally bonded sheet is comprised of about10 to 90 wt % of a bicomponent binder fiber and about 10 to 90 wt % of amedia fiber. The bicomponent binder fiber has a diameter of about 5 to50 micrometers and a length of about 0.1 to 15 cm. The media fiber has adiameter of about 0.1 to 5 micrometers and an aspect ratio of about 10to 10,000. The media has a thickness of about 0.1 to 2 mm, a solidity ofabout 2 to 25%, a basis weight of about 2 to 200 g-m-2, a pore size ofabout 0.2 to 50 micrometers and a permeability of about 2 to 200ft-min-1. The liquid to be filtered may be either an aqueous liquid or anon-aqueous liquid. The media is comprised of about 0.1 to 25 wt % of abinder resin. The media is comprised of a single layer or two or morelayers.

The media is comprised of about 0.01 to 10 wt % of a fluoro-organicagent.

In one embodiment of the invention, the invention is a gaseousfiltration medium for removing mist from air comprising a thermallybonded sheet. The thermally bonded sheet is comprised of about 20 to 80wt % of a bicomponent binder fiber and about 20 to 80 wt % of a mediafiber. The bicomponent binder fiber has a diameter of about 5 to 50micrometers and a fiber length of about 0.1 to 15 cm. The media fiberhas a fiber diameter of about 0.1 to 20 micrometers and an aspect ratioof about 10 to 10,000. The media has a thickness of about 0.1 to 2 mm, asolidity of about 2 to 25%, a basis weight of about 20 to 100 grams-m-2,a pore size of about 5 to 20 micrometers, an efficiency of 5 to 25% at10.5 fpm, and a permeability of about 5 to 500 ft-min-1. The mediacomprises about 0.1 to 10 wt % of a secondary fiber having a fiberdiameter of 0.1 to 15 microns. One example of the media fiber is a glassfiber. The glass fiber is selected from one or two or more sources ofglass fiber where the average diameter of the glass fiber is of about0.1 to 1 micrometer, 0.3 to 2 micrometers, 0.5 to 5 micrometers, 0.75 to7 micrometers, 1 to 10 micrometers, or 10 to 50 micrometers. The mediais comprised of a single layer or two or more layers. The media iscomprised of about 0.01 to 10 wt % of a fluoro-organic agent.

In one embodiment of the invention, the invention is a gaseousfiltration medium for removing particulate from air comprising athermally bonded sheet. The thermally bonded sheet is comprised of about80 to 98 wt % of a bicomponent binder fiber and about 2 to 20 wt % of amedia fiber. The bicomponent binder fiber has a diameter of about 10 to15 micrometers and a fiber length of about 0.1 to 15 cm. The media fiberhas a fiber diameter of about 0.1 to 5 micrometers and an aspect ratioof about 10 to 10,000. The media has a thickness of about 0.1 to 2 mm, asolidity of about 10 to 25%, a basis weight of about 40 to 400grams-m-2, a pore size of about 10 to 30 micrometers and a permeabilityof about 20 to 200 ft-min-1. The media comprises a secondary fiber. Oneexample of the media fiber is a glass fiber. The glass fiber is selectedfrom one or two or more sources of glass fiber where the averagediameter of the glass fiber is of about 0.1 to 1 micrometers, 0.3 to 2micrometers, 0.5 to 5 micrometers, 0.75 to 7 micrometers, 1 to 10micrometers, or 10 to 50 micrometers. The media is comprised of a singlelayer or two or more layers. The media is comprised of about 0.01 to 10wt % of a fluoro-organic agent.

In one embodiment of the invention, the invention is a gaseousfiltration medium for removing entrained liquid from blow comprising athermally bonded sheet. The thermally bonded sheet is comprised of about20 to 80 wt % of a bicomponent binder fiber and about 0.5 to 15 wt % ofa media fiber or a secondary fiber. The bicomponent binder fiber has adiameter of about 5 to 15 micrometers and a fiber length of about 5 to15 cm. The media fiber has a fiber diameter of about 0.5 to 15micrometers and an aspect ratio of about 10 to 10,000. The media has athickness of about 0.1 to 2 mm, a solidity of about 1 to 10%, a basisweight of about 20 to 80 grams-m-2, a pore size of about 5 to 50micrometers, and a permeability of about 50 to 500 ft-min-1. The mediacomprises a secondary fiber. One example of the media fiber is a glassfiber. The glass fiber is selected from one or two or more sources ofglass fiber where the average diameter of the glass fiber is of about0.1 to 1 micrometers, 0.3 to 2 micrometers, 0.5 to 5 micrometers, 0.75to 7 micrometers, 1 to 10 micrometers, or 10 to 50 micrometers. Themedia is comprised of a single layer or two or more layers. The media iscomprised of about 0.01 to 10 wt % of a fluoro-organic agent.

In one embodiment of the invention, the invention is a filtration mediumfor filtering lubricant oil comprising a thermally bonded sheet. Thesheet is comprised of about 1 to 40 wt % of a biocomponent binder fiberand about 60 to 99 wt % of a glass fiber. The bicomponent binder fiberhas a diameter of about 5 to 15 micrometers and a length of about 0.1 to15 cm. The glass fiber has a diameter of about 0.1 to 5 micrometers andan aspect ratio of about 10 to 10,000. The media has a thickness ofabout 0.2 to 2 mm, a solidity of about 2 to 10%, a basis weight of about10 to 50 g-m-2, a pore size of about 0.5 to 10 micrometers and apermeability of about 0.1 to 30 ft-min-1. The media is comprised of abinder resin. One example of the media fiber would be a glass fiberwherein the glass fiber is selected from one or two or more sources ofglass fiber where the average diameter of the glass fiber is of about0.1 to 1 micrometers, 0.3 to 2 micrometers, 0.5 to 5 micrometers, 0.75to 7 micrometers, 1 to 10 micrometers, or 3 to 30 micrometers. The mediais comprised of a single layer or two or more layers. The media iscomprised of about 0.01 to 10 wt % of a fluoro-organic agent.

In one embodiment of the invention, the invention is a filtration mediumfor filtering hydraulic oil comprising a thermally bonded sheet. Thesheet is comprised of about 20 to 80 wt % of a bicomponent binder fiberand about 80 to 20 wt % of a glass fiber. The bicomponent binder fiberhas a diameter of about 5 to 15 micrometers and a length of about 0.1 to15 cm. The glass fiber has a diameter of about 0.1 to 2 micrometers andan aspect ratio of about 10 to 10,000. The media has a thickness ofabout 0.2 to 2 mm, a basis weight of about 40 to 350 g-m-2, a pore sizeof about 0.5 to 30 micrometers and a permeability of about 5 to 200ft-min-1. The media is comprised of a binder resin. One example of themedia fiber would be a glass fiber wherein the glass fiber is selectedfrom one or two or more sources of glass fiber where the averagediameter of the glass fiber is of about 0.1 to 1 micrometers, 0.3 to 2micrometers, 0.5 to 5 micrometers, 0.75 to 7 micrometers, 1 to 10micrometers, or 3 to 30 micrometers. The media is comprised of a singlelayer or two or more layers. The media is comprised of about 0.01 to 10wt % of a fluoro-organic agent.

A method of the invention embodies filtering a heated fluid. The methodis comprised of passing a mobile fluid phase containing a contaminantthrough a filter medium, the medium having a thickness of about 0.2 to50 mm, the medium comprising a thermally bonded sheet, and removing thecontaminant. The sheet is comprised of about 20 to 80 wt % of abicomponent binder fiber and about 20 to 80 wt % of a glass fiber. Thebicomponent binder fiber has a first component with a melting point anda second component with a lower melting point. The bicomponent binderfiber has a diameter of about 5 to 50 micrometers and a length of about0.1 to 15 cm. The glass fiber has a diameter of about 0.1 to 30micrometers and an aspect ratio of about 10 to 10,000. The media has asolidity of about 2 to 25%, a basis weight of about 10 to 1000 g-m⁻², apore size of about 0.5 to 100 micrometers and a permeability of about 5to 500 ft-min⁻¹, the mobile fluid phase having a temperature greaterthan the melting point of the second component. In one embodiment of themethod described the fluid is a gas or liquid. In one embodiment of themethod described the liquid is an aqueous liquid, fuel, lubricant oil orhydraulic fluid. In one embodiment of the method described, thecontaminant is a liquid or solid.

The above described filtration medium can be utilized within a breathercap. The breather cap is operably coupled to a fluid reservoir andenables the ingression and egression of gas when fluid is removed fromor added to the reservoir. The filtration medium enables the breathercap to filter solid particulate from influent gas, which refers to gasflowing from ambient air to the reservoir. The filtration medium alsoenables the breather cap to filter fluid mist from effluent gas, whichrefers to gas exiting the reservoir.

While the invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodifications and this application is intended to cover any variations,uses, or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come with known or customary practice within theart to which the invention pertains and as may be applied to theessential features hereinbefore set forth and as follows in scope of theappended claims.

1-13. (canceled)
 14. A wet laid layer comprising a thermally bonded sheet, the sheet comprising: (a) about 10 to 90 wt % of a bicomponent fiber; and (b) an effective amount of a second fiber to obtain a pore size of about 0.5 to 100 micrometers, a permeability of about 5 to 500 ft-min.⁻¹, a thickness of about 0.2 to 50 mm, a solidity of about 2 to 25%, a basis weight of about 10 to 1000 g-m⁻².
 15. A nonwoven filtration medium comprising: a loading layer having an average pore size of 5 to 30 micrometers, wherein the loading layer comprises bicomponent fibers and glass fibers, wherein the bicomponent fibers have a concentric sheath-core structure; and an efficiency layer having an average pore size of 0.5 to 3 micrometers.
 16. The nonwoven filtration medium of claim 15 wherein the efficiency layer has a permeability of 5 to 30 ft-min⁻¹ and the loading layer has a permeability of 50 to 200 ft-min⁻¹.
 17. The nonwoven filtration medium of claim 15 further comprising a fluoro-organic compound.
 18. A multilayer nonwoven filtration medium comprising: a loading layer having an average pore size of 5 to 30 micrometers; and an efficiency layer having an average pore size of 0.5 to 3 micrometers; wherein one or more layers comprise bicomponent binder fibers and glass fibers.
 19. The multilayer nonwoven filtration medium of claim 18 which has a permeability of 4 to 20 ft-min⁻¹, a wet burst strength of 10 lb-in⁻² to 20 lb-in⁻², and a basis weight of 100 g-m⁻² to 200 g-m⁻².
 20. The multilayer nonwoven filtration medium of claim 18 further comprising a fluoro-organic compound.
 21. A nonwoven filtration medium comprising: bicomponent binder fibers having a fiber diameter of 5 to 50 micrometers; glass fibers having a fiber diameter of 0.1 to 30 micrometers; and monocomponent fibers.
 22. The nonwoven filtration medium of claim 21 which has a solidity of 1 to 25%, a basis weight of 2 to 1000 g-m⁻², a pore size of 0.2 to 100 micrometers, and a permeability of 2 to 500 ft-min⁻¹.
 23. The nonwoven filtration medium of claim 21 further comprising a fluoro-organic compound.
 24. A filtration medium comprising a thermally bonded sheet, the sheet comprising: about 20 to 80 wt % of a bicomponent binder fiber having a fiber diameter of about 5 to 50 micrometers; and an effective amount of glass fiber blended with the bicomponent binder fiber; wherein glass fiber is selected from the sources comprising an average fiber diameter of about 0.1 to 1 micrometer, 0.3 to 2 micrometers, 0.5 to 5 micrometers, 0.75 to 7 micrometers, 1 to 10 micrometers, 3 to 30 micrometers in a combination of two or more sources thereof, and in that said selected sources include the source which comprises an average fiber diameter of 3 to 30 micrometers.
 25. A filtration medium in the form of a thermally bonded nonwoven structure, the medium comprising an amount of bicomponent fibers blended with glass fibers, wherein the bicomponent fibers are concentric sheath/core PET/PET fibers. 